This novel completes one of the most accomplished and interesting science-fiction trilogies of recent years. The first volume, Dark Eden, set up the premise. Two astronauts, Angela and Tommy, are marooned on an eerie non-solar planet; the action takes place six generations later, by which time, as well as various genetic problems caused by in-breeding, their descendants have developed a kind of ancestor-worship mythology. “Gela”, they believe, instructed them to remain in Circle Valley awaiting the “Veekle” that will take them back to Earth. But the expanding population is creating a scarcity of resources, and one young man, John Redlantern – a mixture of Prometheus, Moses and Gilgamesh – goes against the conservative elders and lights out for the Cold Dark. It was a deserving winner of the 2013 Arthur C Clarke award.

The second instalment, Mother of Eden, takes places 400 years after the initial crash. It is almost a novelisation of the theologian Karen Armstrong’s theories put forward in Fields of Blood: Religion and the History of Violence, with the move from subsistence to surplus leading to new forms of hierarchy and specialisation. By this stage, Eden is divided between the Johnfolk – more technologically advanced, with their motto “Become Like Earth” – and the traditionalist Davidfolk, with their shamanistic shadowspeakers who claim to be in contact with Gela. The heroine Starlight attempts a social revolution between the “highs” and the “lows”, and daringly makes public the “Secret Story”, Angela’s liberal message handed down from mothers to daughters. There was a huge amount to admire in both books. Beckett made a genuinely alien ecosystem, explored how stories and histories mutate and change – the Eden dwellers know about a conflict between the Germ Man and the Juice, for example – and formed a distinctive linguistic world, with words doubled as intensifiers, a range of slang terms (such as “do” for kill, and “slip” for sex) and some profoundly inventive oaths.

Now we have Daughter of Eden, the finale. The Johnfolk have launched an all-out attack on the Davidfolk. Angie Redlantern was Starlight’s childhood friend, and is a “batface” – meaning she was born with a cleft palate – who was once apprenticed to a shadowspeaker. The incursion turns her and her family into refugees, and as they journey towards the Circle Valley, she reminisces about her time learning about the religion of Gela, the heresies of the Johnfolk and various other forms of ritual and belief that have evolved. She has an inquisitive and sceptical mind, which stands her in good stead when the novel springs its peripeteia: what would happen to these societies if their Messianic hopes were finally fulfilled – if the old prophecies actually came true?

With wit and invention, Beckett has imagined a scien­tific Genesis about a society and the myths that sustain it

Much of the novel is concerned with the very idea of story. Who owns a particular narrative? How does one resolve contradictory stories? In the characters of the older shadowspeaker, Mary, and the bellicose young Johnfolk leader, Luke Johnson, Beckett elegantly and movingly examines how the fundamentalist mind copes when evidence that contradicts its position emerges. He shows how belief systems can be transformed from the literal to the symbolic and metaphorical, and how a story can be rewritten in subtle ways to align with the narrator’s confirmation bias. He does not, however, depict this solely as a kind of psychopathology of religious thinking. The novel equally stresses the importance of shared stories in forming cohesive societies, and gives due attention to the therapeutic role of story in dealing with grief, injustice and suffering. There are interesting asides about the relationship between the state and religion; and clever speculations on the emergence of taboos (Mary, for example, preaches against homosexuality in the context of a schismatic society where strength of numbers is paramount). It would be too simple to write off the characters’ theologies as hypocrisy, and Beckett shows how wanting to believe can turn into belief, how faith is belief in the unbelievable.

Although it provides a definitive closure to the Eden Saga, there is room for the story to continue, with the tantalising prospect of maybe seeing what a denizen of Eden makes of Earth, and why Earth was so interested in Eden in the first place. Beckett sketches in just enough of the backstory about what has been happening on Earth for it to be the basis of a completely different kind of work. Although there is no shortage of pessimism, there are still chinks of hope. The Eden trilogy is a remarkable achievement: with wit, insight and invention Beckett has imagined a scientific Genesis not just about a society, but about the culture and myths that sustain it. It is both politically astute and theologically compelling.

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